Halo: Mac and PC versions of Halo use Ogg Vorbis for all audio, it seems. The Xiph license and dynamically linked libraries of Ogg and Vorbis are included in the Halo directory. XBox version does not use Ogg Vorbis.

Harry Potter II (Chamber of Secrets): This is unsubstantiated, it was reported on one of the vorbis mailing lists, but there is little evidence either way on this title. EA has been supportive of Vorbis though, so it’s not entirely impossible. If anyone can give us a yay or nay on this, please do.

MotoGP: This motorcycle racing sim uses Vorbis for the music and allows players to drop their own .ogg files into the music dir to listen to them in-game.

Myst IV: Revelation: Fourth game in the Myst series. Uses Ogg Vorbis for all music, speech and sound effects.

Myst V: End of Ages: Fifth and final game in the Myst series. Uses Ogg Vorbis for all music, speech and sound effects.

Nascar Racing Games from Papyrus: They had this to say about their decision and experience:

"We’re using a lot of spoken audio in this title (a first for us) and your codec has allowed us to reduce more than 350MB of audio data to about 40MB, a huge savings of memory and disk space! We are very impressed." — Tom Faiano, Producer

"Incorporating Ogg Vorbis into our codebase was quite painless, and in the end, even refreshing. No fuss no muss. Thank you for your efforts!" — Bill Farquhar, Soundguy du jour

Nexuiz, a fast-paced FPS with roots in Quake I, uses Vorbis for background music. The minstagib mod uses Vorbis for all of its sound.

Operation Flashpoint: This highly successful military simulation/action game from Codemasters uses Vorbis for the in-game music.

Ostrich Runner by Geleos: This funny Russian cartoon-style game for kids and not only kids uses Ogg Vorbis for sound, speech and music.

Ski Jumping 2004: A commerical game that accurately models the activity of ski jumping. The game also contains over 700 Ogg Vorbis files.

Star Trek: Away Team: Vorbis is used for all sound in the game — music, voiceover and SFX. This squad-based strategy game is set in the Star Trek Next Generation universe. (Official website is down, using Mobygames link)

"[The characters' dialog is] around 6GB of .wav files and we needed to compress them for inclusion in the game. We used .ogg files due to it being free of the patent and licensing issues that .mp3 has, although either would have worked." — Ron Gilbert

"The original multilanguage distro took three CDs, and went down to only one after I converted all wavs to oggs. Nifty :) Sadly enough, marketing decided to not have one language per CD anyway (probably to annoy people who migrate) :/ Thanks for a very cool (and easy to use) lib/format!" — Vincent Penquerc’h

True Crime: New York City: GameCube version contains over 11,500 Ogg Vorbis files. It is likely that other platform ports also use the same files (note that the Xbox version uses Windows Media Audio files in place of Ogg Vorbis files)

"We went with Ogg Vorbis due to its excellent playback and compression, and we used it not only for music but also all of the in-game voice. Without it, we never would have been able to fit on two CDs." — 4unrealers.com

Unreal Tournament 2003: This overwhelmingly-popular multiplayer first person shooter PC title uses Vorbis for its music.

Unreal Tournament 2004: Yet another Unreal game which uses Vorbis for the music (What about effects and voice? Does anyone know?). The readme file of the demo even mentions Speex!

The Ur-Quan Masters: Port of Star Control 2 to modern computers. Toys for Bob released the source of this amazing game under the GPL in 2002. Ogg Vorbis is used for the dialogue and the background music.

Lionheart — Legacy of the Crusader: An 3/4 RPG from Black Isle. Uses Vorbis for all audio. Thanks to all the guys that made Vorbis great.. (I even donated money myself, someday maybe I can convince the company to kick in some bucks as well). Official site is down, using mobygames link.